Core-sample and outcrop studies of the Upper Cambrian-Lower Ordovician section reveal new thickness and stratigraphic data for the Saratoga Springs region. Gradationally overlying the Potsdam (Keeseville) Sandstone, the (Upper Cambrian) Galway Formation consists of 47.6 m (157 feet) of quartzo-feldspathic dolostones and minor silicified oolites; the Mosherville Sandstone is recognized as a member of the upper part of the formation. The Hoyt Formation (Upper Cambrian) is 11.8 m (39 feet) of dolomitic limestone that apparently is conformable with overlying and underlying dolostones. The Gailor Formation (Upper Cambrian-Lower Ordovician) consists of a minimum of 77.6 m (256 feet) of quartzo-feldspathic dolostones and includes the Ritchie (10.3 m) and Slade Creek (18.8 m) Members; the latter unit had been unrecognized in the area. Four carbonate depositional environments are recognized in the Galway and Gailor Formations, including a range from shallow marine to subaerial sea-marginal flats. Studies of depositional cycles in these units suggest the local, restricted development of individual sedimentation zones in this area, and the existence of a shoreline complex of peritidal shoals of varying energy regimes interrupted by shallow subtidal shelves. The carbonate shelf environments recognized in this area can be correlated to similar shelf deposits along the southern and eastern margins of the ancestral Adirondack Mountains in New York.